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Sylvie Dufour Nadine Le Belle Sylvie Baloche Yves-Alain Fontaine 《Fish physiology and biochemistry》1989,7(1-6):157-162
Treatment of sham-operated female silver eels with carp pituitary extract stimulated ovarian development and induced increases
in pituitary gonadotropin (GTH) and gonadoliberin (GnRH) contents. Both effects of carp pituitary extract were abolished in
ovariectomized eels, indicating the involvement of the gonads. Endogenous sexual steroids, the secretion of which was increased
during sexual maturation, should be responsible for the stimulation of GTH and GnRH levels. Ovariectomy itself had no significant
effect on pituitary GTH and GnRH contents, reflecting the fact that, at the silver stage, sexual steroid levels are too low
to exert any significant effect on pituitary GTH and GnRH. The positive feedback control exerted by the gonads on GTH and
GnRH levels during sexual maturation, in the eel as well as in some other teleosts, would produce an amplification of the
pubertal stimulation of the hypothalamo-pituitary-gonadal axis. 相似文献
3.
ABSTRACT: Cultured immature female Japanese eels acclimated to sea water at either 10 or 20°C were treated weekly with salmon gonadotropin fraction (sGTH) in order to investigate the effects of water temperature on artificial induction of ovarian maturation. In eels maintained at 20°C, ovulation was induced in 11 of 18 fish during the experimental period of 13 weeks, whereas at 10°C all fish showed a low gonadosomatic index (GSI) at the end of the experiment. Plasma vitellogenin levels were higher in eels kept at 20°C than in eels at 10°C throughout the experiment. However, no significant differences were observed in the plasma testosterone and estradiol-17β levels between groups. Eels pretreated with sGTHs at 10°C for 13 weeks were separated to two different temperature (10 and 20°C) groups, and received the same weekly sGTH injections. In eels transferred to 20°C, plasma vitellogenin levels, GSI and oocyte diameter were increased, but these values were maintained at low levels in eels that remained at 10°C. These results clearly indicate that water temperature is an important factor regulating vitellogenesis in the Japanese eel. 相似文献
4.
鲤脑垂体匀浆液和人绒毛膜促性腺激_省略_性腺激素及性类固醇激素含量的影响 总被引：7，自引：0，他引：7
雄鳗注射５－６次、雌鳗注射９－１０次鲤脑体匀浆液（ＣＰＥ）＋人绒毛膜促性腺激素（ＨＣＧ）能分别诱导精巢和卵巢发育成熟。在雌雄鳗鲡,注射ＣＰＥ＋ＨＣＧ可显著增加端脑、间脑、中脑和下丘脑ｍＧｎＲＨ的含量,而对后脑和延髓ｍＧｎＲＨ的影响较小;注射ＣＰＥ＋ＨＣＧ增加雄鳗后脑和延髓ｃＧｎＲＨ－Ⅱ含量,对雌鳗脑区ｃＧｎＲＨ－Ⅱ则无显著影响。雌雄鳗鲡每次注射ＣＰＥ＋ＨＣＧ后１天,血清促性腺激素（ＧｔＨ）急剧上升 相似文献
5.
6.
ABSTRACT: The nucleotide sequences of Japanese flounder Paralichthys olivaceus , major histocompatibility complex (MHC) cDNA, classical MHC class Iα, non-classical MHC class Iβ, MHC class IIα and IIβ, were determined. The domain structures and antigen binding motifs of vertebrate MHC are conserved in the Japanese flounder MHC. A phylogenetic analysis supports the classification of these genes into class I and class II MHC. Classical MHC class Iα was ubiquitously expressed, whereas the non-classical MHC class Iβ was expressed mainly in lymphoid organs, gills, intestine and stomach. The MHC classes IIα and IIβ were also ubiquitously expressed. 相似文献
7.
ABSTRACT: In order to clarify the roles of androgen and gonadotropin-releasing hormone (GnRH) on gonadotropin (GTH; luteinizing hormone [LH] and follicle stimulating hormone [FSH]) synthesis, effects of castration and implantation of GnRH analog (GnRHa) or 11-ketotestosterone (11-KT) on expression of GTH subunit, α-glycoprotein subunit (αGSU), FSHβ, and LHβ genes, during the early spermatogenic stage in male red seabream Pagrus major were examined. Male red seabream underwent castration or sham-operation and were subsequently implanted with cholesterol pellets containing GnRHa, silicone capsules filled with 11-KT, or blank capsules (control). FSHβ mRNA levels increased due to castration, and it was reversed by treatment with 11-KT. 11-ketotestosterone treatment also decreased FSHβ mRNA levels in sham-operated fish. These results suggest that 11-KT acts on the pituitary to suppress FSH synthesis in male red seabream. On the other hand, neither castration nor replacement of 11-KT in castrated fish had effects on LHβ mRNA levels, whereas 11-KT treatment had slightly but significantly decreased LHβ mRNA in sham-operated fish. αGSU mRNA levels were not changed by castration or 11-KT treatment in both sham-operated and castrated fish. Meanwhile, treatment with GnRHa significantly decreased FSHβ mRNA levels in sham-operated fish, but not in castrated fish. This suggests that GnRHa may down-regulate expression of FSHβ mRNA through the production of 11-KT in testis. LHβ and αGSU mRNA levels in sham-operated fish, but not in castrated fish, were significantly elevated by treatment with GnRHa. 相似文献
8.
Yuichi Ozaki Koichi Ishida Koji Saito Kazuhiro Ura Shinji Adachi Kohei Yamauchi 《Fisheries Science》2007,73(3):574-584
ABSTRACT: Specific antibodies against follicle-stimulating hormone β subunit (FSHβ), prolactin (PRL), and somatolactin (SL) of the Japanese eel Anguilla japonica were produced. These antibodies, as well as antibodies against luteinizing hormone β subunit (LHβ) and growth hormone (GH) produced previously, were used to examine changes in the production of pituitary hormones in female eels during maturation induced by salmon pituitary homogenate (SPH) injection. Immunohistochemical observations showed a decrease in FSH production after SPH injection, suggesting that SPH inhibits FSH production. In contrast, LH production increased markedly with maturation. The number of GH producing cells decreased gradually during maturation, possibly because of inhibition by exogenous GH present in the SPH and/or endogenous insulin-like growth factor-I produced by the stimulation of salmon GH. Although changes in the number of PRL producing cells with maturation were not evident, the number of SL producing cells showed a peak at the late vitellogenic stages, and thereafter decreased to the migratory nucleus stage. These results suggest that GH and SL are involved in sexual maturation in SPH injected eels, as in other fishes. 相似文献
9.
Hiroaki Chiba Kenji Iwatsuki Kazuo Hayami Akihiko Hara Kohei Yamauchi 《Journal of the World Aquaculture Society》1994,25(4):553-560
Changes in serum concentrations of estradiol-17β, testosterone, 17α,20βdihydroxy-4-pregnen-3-one, and vitellogenin were investigated during ovarian development induced by injection of a salmon pituitary extract in cultured European eel Anguilla anguilla . Vitellogenesis was induced with a weekly dose of 50 mg pituitary extract/kg body weight. In eels receiving that dose, gonadsomatic indices ranged from 20–43% after the 10th–11th weekly injection. Body weights were relatively stable during vitellogenesis, but increased dramatically during final maturation. Serum estradiol-17β levels increased slightly during vitellogenesis and peaked at an average of 6.95 ng/mL at final maturation. The profile of serum vitellogenin followed that of estradiol-17β which increased markedly from an average of 0.36 to 20.72 mg/mL. Control levels of vitellogenin were undetectable throughout the study. Average serum levels of testosterone increased to a peak of 17.74 ng/mL in the early stage of vitellogenesis, followed by a sharp drop to initial levels (3.86 ng/mL) in the late stage of vitellogenesis, and then increased again to an average of 8.84 ng/mL at the final maturation stage. Serum 17α,20β-dihydroxy-4-pregnen-3-one was not detected (<50 pg/mL) throughout the experiment. Profiles of serum estradiol-17β, testosterone, and vitellogenin observed during ovarian development appear different from those found in salmonids and other teleosts. This study indicates, however, that cultured European eels are a useful model for study of gonadal maturation in the eel. 相似文献
10.
Gonadal development and expression profiles of gonadotropin genes in wild sea conger, Ariosoma meeki
S. Ishii Y. Yoshiura S. Kajimura N. Mochioka K. Aida 《Fish physiology and biochemistry》2003,28(1-4):95-96
Reproductive physiology of an anguilliform fish, wild sea conger (Ariosoma meeki) was studied. Spawning season of this species is between July and August, and their oocytes showed synchronous development. mRNA levels of GTH subunits increased in accordance with gonadal development and decreased after spawning. Present results were inconsistent with our previous results in artificially matured Japanese eel. 相似文献
11.
Female rainbow trout were exposed over their second reproductive cycle to a simulated natural photoperiod (control group) and to two accelerated photoperiod regimes (S9 and S6 groups). Early spawning was achieved in both accelerated groups, coupled, however, with a reduction of mean egg size. To investigate this reduction of egg size, circulating levels of GTHs and two indices of ovarian growth (gonadosomatic index and follicle diameter) were regularly measured in association with histological studies of structural changes in ovarian follicles. Regardless of the photoperiod regime, the seasonal profile of plasma GTH I levels appeared to be multiphasic. The successive transient elevations in GTH I levels appeared to be connected with the initiation of ovarian growth and vitellogenesis and also, with the synchronization of the late stages of maturation and ovulation. In contrast, the seasonal profile of plasma GTH II levels was monophasic, with a single peak at ovulation, confirming that GTH II is not associated with ovarian growth but promotes gamete maturation and release. Our results demonstrate that the reduction of egg size cannot be due to a deficient secretion of GTH I in plasma, since GTH I levels were much higher during vitellogenesis in both accelerated groups, but rather to an alteration of ovarian follicle growth during the late stages of vitellogenesis. Finally, the early and middle stages of ovarian growth appeared to be photosensitive periods, whereas the late stages were less so, and appeared to be controlled rather by an endogenous biological clock synchronized by the photoperiod. 相似文献
12.
Pham KX Amano M Kurita Y Shimizu A Fujinami Y Amiya N Yamamori K 《Fish physiology and biochemistry》2008,34(4):357-365
The role of gonadotropin (GTH) in the reproduction of the Japanese flounder, Paralichthys olivaceus, was studied by assessing the changes in the apparent activity of follicle-stimulating hormone (FSH) and luteinizing hormone
(LH) in the pituitary gland during gonadal maturation by immunohistochemical analyses. Corresponding changes in plasma levels
of testosterone (T), estradiol-17β (E2), and 17α,20β-dihydroxy-4–pregnen-3-one (DHP) were also studied. Reared fish at the early spawning to termination stages
were sampled from May to August and wild fish at the previtellogenic to termination stages were caught at 3- to 4-week intervals
between April and September offshore from the northern mainland of Japan by gill nets. The gonadosomatic index of the reared
fish decreased from the early spawning stage to the termination stage, while that of the wild fish increased significantly
from the previtellogenic stage to the early spawning stage and decreased thereafter. In the reared fish, the immunostaining
intensities of FSH and LH were high during the spawning period, accompanied by high plasma levels of T, E2, and DHP. In the wild fish, the immunostaining intensities of FSH and LH were low during the previtellogenic stage but increased
during the maturing and spawning stages. These results indicate that both FSH and LH are likely associated with oocyte maturation
in the Japanese flounder. 相似文献
13.
Sonoko Yamaguchi Koichiro Gen Koichi Okuzawa Michiya Matsuyama Hirohiko Kagawa 《Fisheries Science》2006,72(4):835-845
ABSTRACT: In order to investigate the influence of estrogen and androgen on reproductive activities of male teleosts, male red sea bream were implanted with silicone capsules containing estradiol-17β (E2), testosterone (T) or 11-ketotestosterone (11-KT) in immature and early spermatogenic stages. One month after implantation of either E2 or T, the gonadosomatic index decreased in accordance with testicular regression in both stages. Implantation of E2 decreased circulating 11-KT levels but did not affect gonadotropin (GTH) subunits, follicle stimulating hormone-β (FSHβ), luteinizing hormone-β (LHβ), α glycoprotein subunit (αGSU) gene expression, and serum LH levels in both stages. Alternatively, T decreased serum 11-KT and LH levels, and FSHβ and LHβ mRNA levels in the early spermatogenic stage but not in the immature stage. These results suggest E2 may directly inhibit testicular development through the suppression of 11-KT production. Meanwhile, T may decrease serum 11-KT levels through the suppression of FSH and LH secretion, resulting to inhibition of testicular development in the early spermatogenic stage. Treatment with 11-KT did not affect the testis in either stage, whereas 11-KT increased LHβ and αGSU mRNA levels in immature, and decreased FSHβ mRNA levels in the early spermatogenic stage. These results suggest that 11-KT may have different effects on GTH subunit gene expression in each reproductive stage. 相似文献
14.
Michiya Matsuyama Shinji Adachi Yoshitaka Nagahama Katsuhiko Maruyama Shuhei Matsura 《Fish physiology and biochemistry》1990,8(4):329-338
Ovarian developmental stages and serum steroid hormone levels were examined at six different times of day (0100, 0600, 1000,
1300, 1600, 2000 h) in a marine teleost, the Japanese whiting Sillago japonica, which has an asynchronous-type ovary containing oocytes at various stages of development and spawns every day during a period
ranging up to three months. The largest oocytes in the ovaries at the active vitellogenic or post-vitellogenic stages were
found between 0100 and 1300 h. Oocyte maturation indicated by germinal vesicle breakdown (GVBD) occurred at 1600 h, and ovulated
oocytes were observed in the ovaries collected at 2000 h. These processes were accompanied by a significant daily change in
serum steroid hormone levels. The serum level of estradiol-17β showed a peak in fish with mature oocytes sampled at 1600 h.
In these fish, the second-largest oocytes in the ovaries were at the initial stage of vigorous vitellogenesis, the secondary
yolk stage. Therefore the highest level of serum estradiol-17β was considered to be due to the second-largest oocytes. Testosterone
levels remained low and constant throughout the experimental period. The serum levels of 17α,20β-dihydroxy-4-pregnen-3-one
(17α,20β-diOHprog) peaked at 1600 h at which time all fish had mature oocytes. These results indicate that the Japanese whiting
possesses a diurnal rhythm of oocyte development including vitellogenesis, oocyte maturation and ovulation, and further suggest
that daily cycles in oocyte growth and maturation which simultaneously take place in an ovary are regulated by diurnal secretions
of estradiol-17β and the maturation-inducing steroid, 17α,20β-diOHprog. 相似文献
15.
Ky Xuan Pham Masafumi Amano Noriko Amiya Yutaka Kurita Kunio Yamamori 《Fish physiology and biochemistry》2006,32(3):241-248
To elucidate the role of gonadotropin-releasing hormone (GnRH) in gonadal maturation in wild female Japanese flounder Paralichthys olivaceus, we monitored changes in the levels of seabream GnRH (sbGnRH) in the olfactory bulb, telencephalon, hypothalamus, and pituitary during ovarian development together with changes in plasma levels of testosterone (T), estradiol-17β (E2), and 17α, 20β-dihydroxy-4-pregnen-3-one (DHP). Fish were caught offshore of the northern mainland of Japan in the Pacific Ocean at 3- to 4-week intervals between April and September by gill net. The netted fish were categorized into six groups based on ovarian stages: previtellogenic (April–early May), early yolk (April–late May), late yolk (late May–June), early spawning (June–August), late spawning (September), and termination (September) stages. The gonadosomatic index significantly increased from the previtellogenic to early spawning stages and decreased thereafter. In the olfactory bulb, no significant differences were observed in sbGnRH levels among the developmental stages. In contrast, sbGnRH levels in the telencephalon and hypothalamus were very high in the previtellogenic stage, lower in the early spawning stage, and relatively high in latter stages. sbGnRH levels in the pituitary were high in the previtellogenic stage and low in the early spawning stage. In addition, the relatively high levels of pituitary sbGnRH were found together with high plasma T, E2, and DHP levels in fish in the late yolk stage. These results indicate that sbGnRH in the telencephalon, hypothalamus, and pituitary is involved in ovarian maturation and that sbGnRH may play an important role in the initiation of ovarian recrudescence in wild Japanese flounder. 相似文献
16.
Naomi MIKAWA Tomoko UTOH Noriyuki HORIE Akihiro OKAMURA Yoshiaki YAMADA Atsushi AKAZAWA Satoru TANAKA Katsumi TSUKAMOTO Ikuo HIRONO Takashi AOKI 《Fisheries Science》2004,70(6):960-970
ABSTRACT: Estrogen receptor (ER) cDNA was cloned from the liver of common Japanese conger Conger myriaster . Common Japanese conger ER cDNA contains 2543 nucleotides including an open reading frame that encodes 596 amino acids, with a molecular weight of 66.1 kDa. The deduced amino-acid sequence of the common Japanese conger ER shares 85% identity with that of eel Anguilla japonica ER-β, and 39–46% and 53–59% identity with the deduced sequences of ER-α and ER-β of other species, respectively. In a phylogenetic analysis, the common Japanese conger ER was found to cluster with the ER-β of other species. The common Japanese conger ER-β also has six domains (A–F), which are conserved in the nuclear receptor superfamily. The amino-acid sequences in the C and E domains were highly conserved between common Japanese conger ER-β and other ER. However, the other domains showed low homology. In the female common Japanese conger, ER-β mRNA was highly expressed in the liver and pituitary gland. The expression levels of the ER-β gene increased from the oil droplet stage to the primary yolk globule stage and were maintained until the migratory nucleus stage. 相似文献
17.
F.E.M. Rebers C.P. Tensen R.W. Schulz H.J.Th. Goos J. Bogerd 《Fish physiology and biochemistry》1997,17(1-6):99-108
The cDNAs encoding the glycoprotein hormone -subunit (GP) and the gonadotropin II-subunit (GTH II) were cloned from the pituitary gland of the African catfish, Clarias gariepinus. Using RNase protection analysis, we studied the steady-state mRNA levels of GP as well as GTH II in the pituitary gland of adult male catfish. Castration of adult male catfish resulted in a significant decrease of GTH II mRNA levels, whereas there was no change in the GP mRNA levels. Treatment of intact males with a single dose of 11-ketotestosterone (11-KT) resulted in dose-dependent increases in mRNA levels of both GP and GTH II. We conclude that 11-KT, a prominent, non-aromatizable teleost androgen, has a stimulatory effect on the pituitary mRNA levels of GP and GTH II of adult male fish. 相似文献
18.
ABSTRACT: Cultivated eels often either lack a part of the ovary (abnormal) or do not have any gonadal tissue (completely sterile). These abnormalities may cause a failure of induction of sexual maturation of female eels. In order to effectively induce sexual maturation and obtain good quality eggs, female eels having normal ovaries should be selected before induction of maturation. The present study examined effects of injection of salmon pituitary extract (SPE) on serum estradiol-17β levels to estimate gonadal status of sexually immature Japanese eels. At the initial stage (just prior to SPE injection), serum estradiol-17β levels were low and no significant difference was observed among eels possessing the different gonad types (normal, abnormal, and sterile), suggesting that gonadal status cannot be estimated by the measurement of serum estradiol-17β levels. A single injection of SPE significantly increased serum estradiol-17β levels in eels possessing normal and abnormal ovaries, but not in sterile eels. Serum estradiol-17β levels significantly increased from 24 h and were high on day 3. These data indicate that eels possessing ovaries can be distinguished from sterile eels by measurement of serum estradiol-17β between 1 and 3 days after a single injection of SPE. 相似文献
19.
ABSTRACT: Annual changes in the gonadosomatic index (GSI), oocyte diameter, gonadal histology and plasma estradiol-17β (E2 ) levels were investigated in female common Japanese conger Conger myriaster in captivity. Juveniles were caught in September 1999 and reared in seawater at temperatures ranging from 10–20°C for 3 years. All fish were immature when captured in September 1999. GSI and oocyte diameter increased from October 2000, peaked between summer and autumn 2001, and bottomed-out in winter 2001. Plasma E2 level also increased from October 2000, but remained high. The ovarian developmental stage was at the peri-nucleolus stage or the oil droplet stage until September 2000. Vitellogenesis started in October 2000 and oocytes progressed to the tertiary yolk globule stage by summer 2001. However, vitellogenic oocytes regressed in all females after autumn 2001. The neogenetic oocytes began to increase after November 2001 and ovarian development progressed in 2002 as they did in 2001, although maximum GSI in 2002 was half its 2001 value. These data indicate that ovarian development in the common Japanese conger has an annual periodicity, and that these congers may be able to spawn in multiple years under rearing condition. 相似文献
20.
The duality of teleost gonadotropins 总被引：5，自引：0，他引：5
Hiroshi Kawauchi Kunimasa Suzuki Hiromichi Itoh Penny Swanson Nobuko Naito Yoshitaka Nagahama Masumi Nozaki Yasumitu Nakai Seiga Itoh 《Fish physiology and biochemistry》1989,7(1-6):29-38
The duality of salmon gonadotropins has been proved by biochemical, biological, and immunological characterization of two
chemically distinc gonadotropins. GTH I and GTH II were equipotent in stimulating estradiol production, whereas GTH II appears
to be more potent in stimulating maturational steroid synthesis. The ratio of plasma levels and pituitary contents of GTHs
and the secretory control by a GnRH suggest that GTH I is the predominant GTH during vitellogenesis and early stages of spermatogenesis
in salmonids, whereas GTH II is predominant at the time of spermiation and ovulation. GTH I and GTH II are found in distinctly
separate cells. In trout, GTH I is expressed first in ontogeny, whereas GTH II cells appear coincident with the onset of spermatogenesis
and vitellogenesis, and increase dramatically at the time of final reproductive maturation. Comparison of the amino acid sequences
of polypeptides and the base sequences of cDNA revealed that salmon GTH I β is more similar to bovine FSHβ than bovine LHβ
and salmon GTH II β shows higher homology to bovine LHβ than to bovine FSHβ. The existence of two pituitary gonadotropins
in teleosts as well as tetrapods suggests that the divergence of the GTH gene took place earlier than the time of divergence
of teleosts from the main line of evolution leading to tetrapods. 相似文献